Signal system



Oct. 29, 1929. C, A, CAMPBELL SIGNAL SYSTEM Filed Aug. 3, 192B I @annum-tm Cho/11M l. Ca/frLPbd/(f: A (9o Patented Oct.. 29, 1.929

UNITED STATES PATENT oEElcE .N N

CHARLES A. CAMPBELL, OF WATERTOWN, NEW YORK, ASSIGNOR T 'lI-IEv NW YORK i AIR BRAKE COMPANY, A CORPORATION OF NEWJERSEY SIGNAL SYSTEM Application filed August 3, 1928.y Serial No. 297,224.

rihis invention relates to pneumatic signal systems, and particularly to .the type of system commonly used on railroad trains.

In such systems a signal pipe is normally maintained fully charged by a pressure reducing feed valve which is constantly opera-V tive, and which feeds air from a storage volume, which commonly is the main reser* voir of the air brake system. The signal pipe is connected from car to car by suitable hose connectors, and on each car there is aso-called conductors valve, which is merely a valve for venting the signal pipe to atmosphere for the purpose of producing in the signal pipe momentary reduced pressure impulses. These impulses traveling forward in the signal pipe, reach and actuate a signal valve in the cab, and this Vvalve responds to each reduced pressure impulse to vent signal pipe air through a Whistle. When the device functions .props erly the whistle blows a signal blast for each opening of a conductors valve.

In trains of some length, say fifteen cars or over, the systems of the prior art commonly fail to function after a few blasts have been sounded, although the signal code involves as many as seven blasts. Failure'after the second blast yin long trains is a common occurrence. This failure is caused partly by faulty manipulation of the conductor-s valve i.- e., the venting of too much air for each last; partly by leakage frem the signal pipe; and generally by any cause which serves 4to produce an undue reduction of signal pipe pressure. The difficulty is accentuatedv by the fact that the signal valve itself vents signal air to blow the Whistle. y y

I haveV discovered that the important cause ofthe failure to operate is the opening of the feed valve, as a result of depleted signal pipe pressure. This valve opens for a very slight reduction of pressure and commonly functions to permita pulsing feed flow. rI`he positive pulsations thus producedin the brake pipe neutralize or interfere with the negative pulsations causedby the conductors valve, andV the result is that the signal valve does not respondproperly.

he present invention overcomes this difficulty by the use of two novel mechanisms in4 conjunction with signalsystems otherwise of conventional form. While these two devices may be used singly, they produce the best results in conjunction with each other, and can be combined in a unitary structure.

The first of these mechanisms is put into action when the signal is actuated, and serves to prevent the feed valve from feeding air to the signal pipe. The mechanis-m preferably includes a timing device which causes the suspension of feeding to persist for a period longer than the normal interval between'successive signal blasts. In this way feed flow is suspended throughout a series of successive blasts forming a code signal.

The second mechanism provides means for blowing the whistle by main reservoir rair instead of by signal pipe air.V It thus becomes possible to reduce the amount of air vented from the signal pipe by the signal valve and` yet secure a stronger and more certain blast from the whistle.

Generally stated, the air discharged by the signal valve is caused to operate a diaphragm mechanism which controls the blowing of the whistle and which charges the timing reservoir. This timing reservoir has a vent which dissipates the charge in a given period of time, and while the charge persists its pressure acts upon an abutment to close a valve controlling the feed passage. This valve is preferably but not necessarily, distinct from the feed valve. k

The preferred embodiment of the invention isillustrated in the accompanying drawing which shows, partly in elevation, and partly in vertical section, that portion of the signal equipment which is mounted on a locomotive.

`Only a portion of the signal pipe is shown and the conductors valves,rsince they are ofordinary construction lfamiliar gto those skilled in the art have been omitted altogether. i

The supply reservoir is shown at l. The feeding flow from this reservoir occurs through stop valve 2, normally open, an automatic pressure reducing feed valve 3, of

ordinary construction, and a strainer 4, of

ordinary construction. y

In the conventional system this feed How y pipe tothe signal valve. posed 1n this connection in order to restrict would be directly to the signal pipe 5, which, as stated, extends throughout the train, being connected from car to car by hose connectors, one of which is shown at 6. In the present device, however, the feed controlling mechanismfis interposed in the path of flow to the signal pipe 5,` and this mechanism, as well as the signal valve, is supported on abracket .structure 7, which contains a relatively large "timing lreservoir 8 and anumber of ports and passages hereinafter described..

Bolted to a ported face on the lower-side of the bracket 7 and communicating` with the chamber 8 by means of a'passage 9 is a housing made up of two castings 11 and 12. This housing contains the feed interrupting valve proper. -The pipev 13 which leads the air l from the-filter 4 communicates with a port S14 formedin the members 7, 11 and 12, and

leading to the'under side of a valve seat 15.

*From'the space above this seat there leads a '1 'passagef16 which communicates with the siglIna-l valve hereinafter described. A branch pipe 17: serves as a connection from the signal `A-choke 181s interthe flow, and thus preclude over-stressing of Athe .signal valve diaphragm, particularly whilefcharging the device. y

Mounted in the casting` 11 cylinder bushing 21 which makes a close slipt in the casting and issealed by the gasket 22 which f also seals the-joint between the castings 7 and 11. iWorkingin the cylinder r21 is a piston 23 having a through bleed' port 24 which is the timing port through which the chamber 8 is vented after it has been charged. The

k'space belowlthepiston23isvented to atmosz"p'he'r'e'by the passage 25. von a valve y`stem26 which Ycarriesa valve 27 The piston 23 is fast arranged to coact with Athe seat .15. 4The ychamber 28,'-which-is above the scat 15 iand in'commu'nication with the passage 216, is isolated fromi the space below the pistoni 23 lby a partition 29. This isolation is'.V further "maintainedbythe factthat when the valve E27-His I inf its- Lupperl position it seats and seals against a guide bushing 31 fixed in the partition' 29. The piston 231sv urged Yupward to lopen thevalve 27 by. means of a coil springy 32 which surrounds the `valve stem 26.` Y

' The normal condition ofthe partsfis with 'the piston 23 in its Vupper position, lthe *chamber 8 vented to atmospheric pressure, *and the valve 27 open. The Vsignal valve above alluded to Vincludes a 'bracket portion 33 "'whichfisbolted to the member 7 iand sealed thereagainst by means of a gasket 34, ai d the lower portion 35 which contains a bal- 60 1 y#member 33 `is 'formed 'with a diaphragi a'ncing chamber or reservoir 36. The-bracket chamber 37f'and` the chambers 36 and v37 lare isolated 4from 'each other bya di aphragm 38 which also serves asa gasket between. the

iparts33 and? 35. The diaphragm 38 carries a pair of stiffener plates 39 which engage opposite sides of the diaphragm and are clamped together by a hub 41 and a nut 42. The hub is provided with an axial restricted port 43 into the lower end of which projects a tapered guide and throttling pin 44 -fixed in the member 35. 'There is also a lateral port 45 which leads to the port 43 in the hub, and is smaller than port 43.

Hub 41 carries three i pins VX46, 'two "of Vwhich are visible in the drawing, and these are designed to engage va disk or plate 47 fast on a check valve 48 which seats downward against the seat 49 and is held against chattering by a light spring 51. The valve v48 is guided by a stem which worksin a guideway Vformed .in Athe Vplug .or cap 52. The port 16 after passing through the choke Vlff'connects withthe chamber 37. The valve '48 controls flow from the chamber 37 to 'a porty 53 which extends through the bracket member 33 and through the'memb'er 7. The port 53 y'communicates through a chokeport 54 with an adjacentiport 55 also formed in .the member 7, kand this port 55 communicates through pipev56 with a signal Awhistle 57.

Thereiis a by-pass connection 58 which leads fromthe reservoir V1, or, to bemore accurate, from a point betweenthe cock'2.

and feed valve 3,\to a passage 59-formed in the casting 7. Bolted to thevcasting 7, and

vsealed-thereto by'means-'of Val gasket 61,1is Aa-housing 62 which contains extensions lof rings are held by spider nuts 69-anfd 71.

The spider nuts are ported sothatrthespace 72 below 'the diaphragm 66-communicates directly with thechamber- 8, and the spacey 73 above theV diaphragm 65 communicates directly with the passage 55. 'Therspider nuts 69, 71, act as partitions between the chambers 72 and 73, on-the Onehand, andV chambers 74 andA 75, onv the other hand.

The chambers 74 and 75 areforme'dfin caps 76V and '77 boltedto the member62, and these chambers are in communication with branches vof the 'passage l59 softhat cham- -bers 74 and 75 are yalways at-the pressure existing vin reservoir 1.

Each vof the spider nuts 69 and '71 is proi vided with a check valve4 Ywhich controls flow from the chamber 74-.tot-he chamber 72," or from the chamber 75 tothe'chamberY 73 as the case maybe. In the member 69 there isa seat bushing 7 8 with-which `coacts Va check valve-79, having a vguidestem 81 and a seating spring-82. 'l This valve has a pilot 83 which abuts against a bearer plate 84 seated against the diaphragm 64. Similarly a seat bushing 85 ismounted in the spider 7l and withthis coactsthe valve 86 having a stem 87 andpseating spring 88. The pilot is shown at 89 and vcoacts with thebearer plate 91 which seats against the diaphragm 65.

With the parts so arranged, let us asA sume that all conductors valves are closed, and that reservoir l is charged. The system will be charged as followsz'Main reservoir air will flow directly through the pipe 58 and charge the chambers 74 and 75 to reservoir pressure. At the same time flow will occur with a reduction of pressure f through the feed valve'3, strainer 4,I pipe 13, passage 14, passage 16 to the signal pipe 5, charging this to the desired pressure, say fifty pounds per square inch. At the same time restricted flow will .occur through the choke 18; This pressure will tend to depress the diaphragm 38, but the effect of the choke 18 is such as to prevent overstressing of the diaphragm.` Once the chamber 37 has been partly charged flow will commence from the passages 43 and 45 to charge the chamber 36. With these conditions valve 48 will be closed and the space 66 between the diaphragms 64 and 65 will be vented to atmosphere by way of choke 54 and whistle 57. Chamber 8 will remain at atmospheric pressure which is established through the vent port 24.

Upon a proper reduction of pressure in the pipe 5, such as would be created by a manipulation of the conductors valve, a wave of reduced pressure will be causedy to move forward in the pipe 5 and pass through the branch 17 to the space 37 above the diaphragm 38. Because of the throttling action f of the part 45 diaphragm 38 will immediately move upward, unseating valve 48, but this unseatmg action will be momentary only because of the increased passage Offered through 43 when the diaphragm moves upward. viously, therefore, the diaphragm will immediately resume its normal position, allowing valve 48 to close. However, the momentary opening of valve 48 allows signal pipe air to flow by passage 16, choke 18, valve seat 49V and passage 53, to the chamber 66 between the dia-r phragms 64 and 65. The pressure in the chamber 66 will persist until dissipated by leakage through the small choke 54.` While the pressure in 66 persists the diaphragms will be forced apart, unseating the valves 79 and 86. The unseating of valve 86 allows reservoir air to flow from the chamber 75 by way of chamber 73, passage and pipe 56, to the whistle 57 which sounds a sharp and clearly audible blast. VThe ,unseatingof valve 79 allows reservoir air to flow by way of chamber 72 and passages 63 to the timing chamber 8, which it charges.

The result of the increased pressure in chamber 8 is the depression of the piston 23 and consequently the seating of the valve 27. The valve 27 will be held closed until the bleed port 24 has vented't-he chamber 8 sufficiently to permitthe spring 32 to forcethe piston upward. The parts are so dimensioned that the period of persistence will be several seconds, say two or three seconds longer than the normal interval between signal blasts.

Since the chamber 8 is charged for each blast it follows that after the first blast, and for a definite period after the last blast, the valve 27 will be held closed. This will preclude, during the entire signal period, the feeding of any air 1 to the signal pipe 5. However, the total volume of the signal pipe is sufficient to furnish the necessary air to actuate the signal valve. The practicability of the scheme, however, is greatly enhanced by the fact that the signal valve does not vent from the signal pipe sufficient air to blow the whistle 57, but vents merely the decidedly smaller quantity necessary to' charge the chamber 66. The signal can ber repeatedly operated inthe manner described, and the pos sible number of blasts therefore exceeds any requirements of service. None-the-less the gradual depletion of pressure inthe signal pipe 5, which is a necessary incident to the repeated successive blasts, does lnot affect the loudness of the signal given by the whistle 57', for the reason that the whistle is blown by main reservoir air and not by signal pipe air.

While I have described one embodiment in particulary detail, I do not imply thatthe invention is necessarily limited to this embodiment, and contemplate possible modifications within the scope of the appended claims. While systems of Vthis sortfare ordinarily operated by air, it is apparent that analogous pressure fluids 'might be used, and no limitation to air alone is implied.

Vhat is claimed is l.. The'combination with a signal system of the type including a signal pipe, automatic vmeans 'for feeding pressure fluid thereto, a Asignal .device and valve means actuated by a depression of signal pipe pressure to actu-k ate thesignal device; of means actuated by such depression of signal pipe pressure for temporarily suspending the feeding function of said pressure fluid feeding means.

2. The 'combination with a signal. system of the type including a signal pipe, automatic means for feeding pressure fluid thereto, a signal device and valve means actuated aya depression of signal pipe pressureto actuate Ythe signaldevice; of means actuated by such `depression of signal pipe Ypressure for temporarily suspending the feeding function of "said pressure fluid'feedi'ng means; and a timing deviee to cause said suspension-'to persist 1 Afora definiteperiod. y

3. The combination with a signalfsystem of the type includingv a signalpipe, lautomatic .gxmeans 'for feeding Vpressure :fluid *.thereto, Aa .signal'whistle and a signal valve device actusaid reservoir with said whistle @a timing chamber having;l a.. bleedjport aseeondivalve `epere'tbleby said ventedzluid tofcharge said timing nehamber from said @reservoir and: a pressurev actuated gvalve :controlling ;tlow throughsaid lfeed valve '1 and arranged to be ated by :a depression; of .signal piper pressure, held,Closedbyjpressureinf s'aidgvented timing of means controlledfb -saidsignal valve:l de- ',vice 'for blowing `sai whistle byfmeans of l1'() pressure fluid fromv a. source other =than the signal. pipe and. means also controlled; by the loperation .of` said valve device to .suspend temporarily the Vvfeeding afunetion -of .said .pressure fluid `feeding means.

,15 4. vThe combination fwith asignalsystem oli the typel including asignal pipe,-auto1natic `means .for Y'feeding :pressure `Huid lthereto, `a signal whistle andza signall valvegdevice ac- .tuated by .adepressiono'f signal pipe pressure, of means controlled by; said ysignal valve device for blowing:y said `whistle by means of ,pressure lluidifrom a .source otheihthan the signal pipe; .y means also 'controlled `by rthe `operation of said `valve -devce to suspend aatemporarily thevfteedingi'unction bf `said pressure fluid `feeding A means and t a i timing `device toeause saidsuspension to` persist lfora definite period. .'5. Inra signaIfSyStem, Vthe combination-ot .30 .a supplysreservoir;.iav signal pipe; apressurefmaintaining feed valve finterposed 'between :said reservoir :andpipe ;'a.signa1 valve operable by'a depression .of signal pipe pressure to vent pressure.luidffromthezsignal pipe; 35. a,signal whistleyand valvemeans operable by .said vented' iuid to connect said reservoir with the whistle.

6. .'In ia. signalisystem, z-the ycombination of asupplylreservoir ;f1asignal pipe; a `pressure- .40 nia-intaining :feed `valve interposed between .1 said 'reservoirzand pipe af signal :valve `operable bya depression of signal pipeipressure to -vent pressure fluid `fromthe Isignaljpipe; yfa

signal Whistle and' valve means operable by -said vented .fluid to iconnectesaid reservoir with the Whistle .and :interrupt Aiiowuthrough the feed valve.

v'Z'. In a. signahl system,the. combination of a supply .reservoir a. signalpipe apressure-V maintaining .feed :valve interposed between said reservoir and pipe ;;a signal valveioperable by a .depression ofisilgnalpipe pressure to vent .i pressure .fluid ffrom the Vsifgnali pipe;

:a signal whistle;valve means f. operable by said vented 'fluid to connectisaidf'reservoir With'the whistle and interrupt flow through .the feed valve ;.andftiming meansfon .causing said interruption topersist.

8. `Ina signal system, thescombination.l of

G0 `a supply reservoir asignalpipe ai pressurevmaintaining .feed valve interposedbetween .l said reservoir and 3' pipe fa :si'g'nallvalve oper- --able by a vdepression .of signal .pipepressuneto i vent i pressure Vfluid from the signal l,pipe :1a 05 valve operableby saidaventedlu-idtooennect l chamber.

19. 4The i ,combination with a signal e .System ofthetype including asignal pipe, .af storage reservoir, a pressure-maintaining -feed valve for feeding,pressureluidjfrom the reservoir tothe. train pipefand-a :signal walve. operable byfa reduction: offsignal pipefpressure; to vent pressureqfluidfrom the signalipipe, o'f-a timing chamber lhgaving a bleed port; ifa valve operable by; saidivented fluid to ,-chargeazsa-d timing chamber :from xsaid reservoir la pressure actuated lvalve controlling flow 

